1. Field of the Invention
The present invention relates to a circuit breaker for on-off switching and protection of a low-voltage circuit, and more specifically relates to an on-off switch mechanism for on-off switching actions of a movable contact element.
2. Description of the Related Art
The aforenamed on-off switch mechanism usually comprises an operating handle that is operated to rotate with a handle shaft as a fulcrum, an on-off switch lever that is so supported as to rotate freely via anon-off switch shaft and that is applied with some force in one direction by a main spring and a mechanism member for transmission of operation of the operating handle to the on-off switch lever, and has a structure wherein, when the operating handle is operated to rotate to ON side, with some force being accumulated in the main spring, the on-off switch lever is rotated to ON position to connect a movable contact element to close an electric circuit but, when the operating handle is operated to rotate to OFF side, with energy of force accumulated in the main spring, the on-off switch lever is rotated to OFF position to disconnect the movable contact element to open the electric circuit. A series of members from the operating handle to the on-off switch lever are usually engaged inseparably with a shaft that penetrates the members and the while on-off switch mechanism is assembled as a single unit inside the circuit breaker.
As for the on-off switch mechanism, specifications of the main spring are varied by rated current while width of on-off switch lever is varied by dimensions of the casing. Therefore, since the entire on-off switch mechanism of the prior art is inseparably engaged as a single unit, the on-off switch mechanism has been assembled individually in accordance with combination of the rated current and the casing dimensions. The conventional on-off switch mechanism, however, wherein those for the same rated current but of different casing dimensions are separated by types, results with large variety of assembly items and complicated assembly operations and parts control hinders cost reduction.
An object of the invention is to decrease variety of on-off switch mechanism assembly items and to simplify the assembly operations and parts control while flexibly coping with the combination of the rated current and the casing dimensions.
According to a first aspect of the present invention, there is provided a circuit breaker on-off switch mechanism which comprises: an operating handle that is operated to rotate with a handle shaft as a fulcrum, an on-off switch lever that is so supported as to rotate freely via an on-off switch shaft and that is applied with some force in one direction by a main spring and a mechanism member for transmission of operation of the operating handle to the on-off switch lever, wherein, when the operating handle is operated to rotate to ON side, with some force being accumulated in the main spring, the on-off switch lever is rotated to ON position to connect a movable contact element to close an electric circuit but, when the operating handle is operated to rotate to OFF side, with energy of force accumulated in the main spring, the on-off switch lever is rotated to OFF position to disconnect the movable contact element to open and break the electric circuit;
wherein an operating part that comprises the operating handle and mechanism member and an on-off switch part that comprises the on-off switch shaft, the main spring and the on-off switch lever are constructed as separate units and that the operating part and the on-off switch part are so engaged as to be disengaged and re-engaged freely.
In the on-off switch mechanism in accordance with the first aspect of the invention, since the on-off switch part, which includes the on-off switch lever of a width that is varied by the casing dimensions and the main spring of which specifications are varied by the rated current, and the operating part, which is used in common without relevance to the rated current or casing dimensions, are structured as the separate units that are so engaged as to be disengaged and re-engaged freely to constitute the on-off switch mechanism, various types of on-off switch mechanisms can be formed freely through combination of the common-use operating part and the specification-conforming on-off switch part, and thus there will be no need to prepare a large number of on-off switch mechanisms assembled in advance.
According to a second aspect of the present invention, the simplest way to engage the operating part with the on-off switch part is to dispose the transmission shaft provided on the mechanism member orthogonally against an interlock shaft provided on the on-off switch lever so that the operating part is engaged with the on-off switch part.
According to a third aspect of the present invention, in the on-off switch mechanism according to the second aspect of the invention, with a hook part that is formed by bending a tip of the mechanism member where the transmission shaft is attached to in such manner that this hook part can be engaged with the interlock shaft of on-off switch lever, the hook part can engage with the interlock shaft of the on-off switch lever so that the actions of the operating part can be unified with those of the on-off switch part in a case where rotating of the on-off switch lever is disabled by the movable contact element that is locked by such a cause as fusing of the contact point.
According to a fourth aspect of the present invention, in the on-off switch mechanism according to any of the first through the third aspect of the invention, a pair of on-off switch shafts on the right and left may be fitted onto projections that are provided on both sides of the on-off switch lever so that a larger space will be reserved inside of the on-off switch lever.
According to a fifth aspect of the present invention, it is desirable that a transmission groove for transmission of mechanical signals to outer packaging accessories is provided in a diametric direction on an end surface of the on-off switch shaft.
According to a sixth aspect of the present invention, two or more of the transmission grooves are additionally provided in different directions on a selfsame end surface of the on-off switch shaft.